Singer Jamie Cullum has said his immaturity prevented him from understanding the “true levels” of his friend Amy Winehouse’s addiction.

The jazz and pop musician toured with Winehouse before her death in 2011 at the age of 27 following a battle with drugs and alcohol.

Cullum, who recently penned a song for the late singer, said he had been inspired after rediscovering text messages they sent to one another in the early 2000s.

Amy Winehouse died in 2011 (Yui Mok/PA)

The 39-year-old said reading the messages made him “just so unbelievably sad” because he saw Winehouse as a “genius”.

Speaking on BBC Radio 5 Live, he said: “I don’t think I was really mature enough to understand what was happening to her at that point, the true levels of her addiction.

“She was the kind of person, it reminded me of myself, where if the night wasn’t good, who would be like, ‘Let’s go back to someone’s house and listen to records’.

“And she was that kind of person and I was like, ‘That’s totally my type of person’.”

Explaining how he came to write The Age Of Anxiety, from his new album Taller, he added: “I thought I’d just look inwardly and think about the things that make me feel anxious and just generally confused.

Flowers outside the home of Amy Winehouse in Camden (John Stillwell/PA)

“One of the things that happened in the last couple of years whilst I was writing, I was clearing out my own studio and I found an old BlackBerry. I plugged it in and found all my old text messages between me and Amy Winehouse.

“We toured together and we were friends in the early 2000s, for a good kind of four to five years before Back To Black.

“Just reading them text messages and seeing how it was at one time and watching it unfold just broke my heart. It was just so unbelievably sad.

“I can safely say I knew she was a genius, no question, I knew her as the music nerd type who just used to always talk about Ray Charles and Nat King Cole and Frank Sinatra.”

Winehouse was best known for hits including Rehab, Back To Black and You Know I’m No Good.

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